1. Field of the Invention
The present invention relates to a thermoplastic resin composition having improved resistance to heat and impact.
2. Description of the Prior Art
Heretofore, graft compolymers composed of styrene, maleic anhydride and rubbery polymer have been widely used, and it is known that both heat and impact resistances can be improved by combining the graft compolymer with an aromatic polycarbonate (see, Japanese Patent Laid-Open No. 92950/1981).
However, when the content of a rubber-reinforced resin such as ABS resin exceeds that of the aromatic polycarbonate in a resin composition containing the aromatic polycarbonate combined therewith, the dispersibility of the rubber is poor and a composition having satisfactory physical properties in respect of resistance to heat and impact, or the like has not yet been proposed.
We have found that when the graft copolymer composed of an aromatic vinyl compound, an unsaturated dicarboxylic acid anhydride and a rubbery polymer predominates in the composition consisting of said copolymer and the aromatic polycarbonate, there can be obtained a composition in which the rubber component is well-dispersed and which is stable and excellent in heat resistance, but the composition is not considered to be satisfactory with respect of impact resistance.
We have made studies to find a composition which is free from disadvantages associated with the prior art and have found that when a methacrylate ester composite modifier is used as a modifier which is well compatible with the above graft copolymer and capable of imparting sufficient impact resistance, the disadvantages mentioned above can be eliminated. The present invention is based on this finding.